Treatment methods for lacrimal duct obstruction resulting in epiphora include: (i) probing by a lacrimal duct bougie, (ii) placement of a lacrimal duct tube; (iii) dacryocystorhinostomy (DCR); (iv) lacrimal canaliculization; (v) nasolacrimal duct plastic surgery; (vi) lacrimal caruncle moving surgery, and the like.
The probing by a lacrimal duct bougie in (i) is intended to insert a narrow tube called bougie into a lacrimal duct to open an obstructed site and reconstruct a flow path for a lacrimal fluid. This method is conducted as a first treatment in many cases due to its ease of execution and minimal invasiveness. The treatments (iii) dacryocystorhinostomy (DCR), (iv) lacrimal canaliculization, (v) nasolacrimal duct plastic surgery, and (vi) lacrimal caruncle moving surgery are highly effective but relatively invasive because of the need for creation of incisions in a patient's face or drilling holes in bones, and thus are conducted as a last resort.
Lacrimal duct tube for use in the treatment method (ii) is, after the probing by a lacrimal duct bougie (i), placed for maintaining of a flow path and reconstruction of tissues. The placement of a lacrimal duct tube (ii) is easy, less invasive, and highly effective as compared to the foregoing treatment methods (iii) to (vi), and thus is widely performed all over the world. Among such instruments, there is widely available a lacrimal duct tube in which a central part of the tube is formed by a narrow and soft tube or rod and both sides of the tube are formed by hard and thick tubes, as disclosed in Patent Document 1 (for example, refer to FIG. 1).
The lacrimal duct tube includes a tube and a pair of bougies that is inserted from incisions at both sides of the tube, and the bougies are operated to guide the tube into a lacrimal duct and place the tube there. As shown in FIG. 2 of Patent Document 1, a lacrimal duct is formed by lacrimal puncta (21 and 22), lacrimal canaliculi (23 and 24), a lacrimal sac (26), a nasolacrimal duct (27), and others. The lacrimal duct tube is inserted into the lacrimal duct.
However, to insert the lacrimal duct tube, it is necessary to fumble for intra-lacrimal duct operations. The bougies are blindly operated and thus may break through the tube or make a hole at a site other than in the normal lacrimal duct (creating a temporary path), which results in poor therapeutic outcomes. Accordingly, to solve the foregoing problem, the inventor of the present invention has suggested in the past a lacrimal duct intubation instrument in which an opening is formed at the tip of lacrimal duct tube, a reinforcement body is arranged and held in the vicinity of the opening, and the position of the reinforcement body is adjusted within a predetermined distance from the opening (refer to Patent Document 1).
In the recent year's field of lacrimal duct obstruction treatment, surgeries have been newly conducted based on a sheath guided endoscopic probing. At these surgeries, a sheath as an outer casing made of Teflon (registered trademark) or polyurethane covering a lacrimal endoscope was advanced ahead of the lacrimal endoscope in the lacrimal duct to observe from behind that the tip of the sheath opens the obstructed site in the lacrimal duct. This technique is also excellent in allowing exact tube insertion by using the sheath as a guide for tube insertion. Specifically, as shown in FIG. 11(a), a sheath 30 attached to a lacrimal endoscope 29 is inserted into an obstructed site 32 in the inferior nasal meatus 28 of the lacrimal duct 31 from the upper lacrimal punctum 21 through the upper lacrimal canaliculus 23 and passed through the obstructed site 32, and then the lacrimal endoscope 29 is removed. Next, as shown in FIG. 11(b), a lacrimal duct tube 33 is connected to the sheath 30, and the sheath 30 is pulled from the side opposite to the connection side of the lacrimal duct tube 33 to let the lacrimal duct tube 33 pass through the lacrimal duct 31. Then, as shown in FIG. 11(c), the sheath 30 is removed to place the lacrimal duct tube 33 in the lacrimal duct 31.
Next, although not shown, a sheath 30 different from the sheath 30 attached to the lacrimal endoscope 29 is inserted into the obstructed site 32 in the inferior nasal meatus 28 of the lacrimal duct 31 from the lower lacrimal punctum 22 through the lower lacrimal canaliculus 24 into which the lacrimal duct tube 33 is not inserted, and after the sheath 30 is passed through the obstructed site 32, the lacrimal endoscope 29 is removed. Then, an end of the lacrimal duct tube 33 not passing through the obstructed site 32 is connected to the sheath 30, and the sheath 30 is pulled from the side opposite to the connection side of the lacrimal duct tube 33 to let the other end of the lacrimal duct tube 33 pass through the lacrimal duct 31. Finally, the sheath 30 is removed to place the lacrimal duct tube 33 in the lacrimal duct 31.
However, according to the foregoing method, there is the need for a step of connecting the sheath inserted into the patient's lacrimal duct to the lacrimal duct tube. In addition, occurrence of the disconnection may result in an unsuccessful surgery. Thus, there is room for improvement in the method to secure manipulation of the instruments and reduce complexity of the operation.
Meanwhile, instead of using such a sheath, a lacrimal endoscope may be inserted into a lacrimal duct tube. For example, as lacrimal duct tubes usable with a lacrimal endoscope therein, there are known: 1) a lacrimal duct intubation instrument as described in Patent Document 1 that has an opening at the extreme end of a lacrimal duct tube and a reinforcement body arranged and held in the vicinity of the opening, the position of the reinforcement body being adjusted to be at a predetermined distance from the opening; and 2) a lacrimal duct treatment tool including a lacrimal duct placement main body that has an outer diameter allowing insertion into the lacrimal duct and is formed from a flexible material and a sheath part composed of a flexible cylindrical body that is provided at the lower end of the lacrimal duct placement main body and is formed from a harder material than that for the lacrimal duct placement main body (refer to Patent Document 2).
However, in the case of using the sheath guided endoscopic probing, the 1) lacrimal duct intubation instrument has a complicated tube structure, and the reinforcement body cannot be significantly smaller in diameter, and the extreme end of the tube is difficult to harden and thus tends to be slightly weak in pressing force (pushability). In addition, when performing operations with the 1) lacrimal duct intubation instrument, it is necessary to carefully operate the endoscope inserted into the tube because friction between the lacrimal duct tube and the endoscope becomes large.
The 2) lacrimal duct treatment tool is entirely long, which tends to make it difficult to perform smooth operations in general. In addition, it is necessary to separate the lacrimal duct treatment tool main body and the sheath part after placement of the tool in the lacrimal duct.